Recently, the demand for portable electronic products such as notebooks, video cameras, cellular phones or the like has rapidly increased, and electric vehicles, energy storage batteries, robots, satellites have been actively developed. For this reason, high-performance secondary batteries allowing repeated charging and discharging are being actively studied.
Currently, nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium secondary batteries, and the like are used as commercial secondary batteries. Among them, lithium secondary batteries have little to no memory effect in comparison with nickel-based secondary batteries, and thus lithium secondary batteries are gaining a lot of attention for their advantages of free charging or discharging, low self-discharging, and high energy density.
A lithium secondary battery generally uses lithium oxide and carbonaceous material as a positive electrode active material and negative electrode active material, respectively. The lithium secondary battery includes an electrode assembly in which a positive electrode plate and a negative electrode plate respectively coated with the positive electrode active material and the negative electrode active material are disposed with a separator being interposed between them, and an exterior, namely a battery case, which seals and accommodates the electrode assembly together with an electrolyte.
Generally, a lithium secondary battery may be classified into a can-type secondary battery where the electrode assembly is included in a metal can and a pouch-type battery where the electrode assembly is included in a pouch of an aluminum laminate sheet, depending on the shape of the exterior.
Recently, secondary batteries are widely used not only for small-sized devices such as cellular phones but also middle-sized or large-sized devices such as vehicles and power storages. In particular, along with the exhaustion of carbon energy and the increased interest on environments, hybrid electric vehicles and electric vehicles attract attention globally, for example in US, Europe, Japan and Korea. In such a hybrid electric vehicle or electric vehicle, a battery pack for giving a driving force to a vehicle motor is the most essential part. Since a hybrid electric vehicle or electric vehicle may obtain a driving force by means of charging and discharging of the battery pack, the hybrid electric vehicle or electric vehicle has many advantages in various aspects, for example excellent fuel efficiency and no or reduced exhaust of pollutants, and for this reason, hybrid electric vehicles and electric vehicles are used more and more.
The battery pack of such a hybrid electric vehicle or electric vehicle includes a plurality of secondary batteries, and the plurality of secondary batteries is connected to each other in series or in parallel to enhance capacity and output. A general battery pack, including the battery pack for a vehicle, includes a cell assembly having a plurality of secondary batteries in a stacked form and a pack housing for receiving the cell assembly in an internal space thereof. In addition, in order to use the battery pack, the battery pack should be electrically connected to an external device by means of a connection member such as a connection wire and a bus bar, and for this connection, an electrode terminal may be provided at the battery pack. In particular, for easily coupling with the connection member, the electrode terminal is frequently formed to protrude outwards at the pack housing and thus be exposed outwards. Therefore, if one end of the connection member is coupled to contact the electrode terminal and the other end of the connection member extends from one end and is connected to an external device such as a motor, a driving power may be supplied from the battery pack to the motor.
However, in this configuration of the battery pack, since the electrode terminal is exposed outwards, several problems may occur. For example, if the electrode terminal is exposed outwards, a conductive substance such as a bolt, a metallic piece or a wire may come into contact with the electrode terminal, and this may cause an electric short circuit. In addition, such contact of a conductive substance may damage the battery pack or other electric systems and also cause sparks, which may result in fire. Therefore, in an existing technique, various attempts have been made to reduce or eliminate the exposure of the electrode terminal. As a representative example, a terminal cover is provided to cover the electrode terminal.
However, in this configuration, even though the safety may be improved by reducing the exposure of the electrode terminal by means of the terminal cover, the battery pack may not be applied to various kinds of devices. In other words, the connection member for connecting to the electrode terminal of the battery pack may have various approaching or extending directions depending on a device to which the battery pack is applied. For example, on the basis of the same battery pack, a connection wire may approach from a left side to connect to the electrode terminal so as to extend in a left direction of the electrode terminal, or the connection wire may also approach from a front side to connect to the electrode terminal so as to extend in a front direction of the electrode terminal. However, if the battery pack includes the terminal cover, since an exposed portion of the terminal cover is restricted, if an approaching or extending direction of the connection wire is changed, the corresponding terminal cover may not be used, and another kind of terminal cover should be used. Therefore, if the existing configuration as described above is used, the battery pack has deteriorated compatibility depending on the kind of device to which the battery pack is applied.